Recently, as semiconductor devices have been more miniaturized, substrates having a fine structure (substrates in which various material films having different physical properties are formed) are processed. For example, in a damascene wiring forming process in which a wiring groove formed in a substrate is filled with metal, excess metal is, after the damascene wiring forming, polished and removed by a substrate polishing apparatus (CMP apparatus) to form various material films having a different physical property in a substrate front surface (a metal film, a barrier film, an insulating film and the like). Such a substrate front surface has a slurry residue and a metal polishing waste (such as a Cu polishing waste) that were used and left in the CMP polishing. Accordingly, when a substrate front surface is not sufficiently cleaned, such as when a substrate front surface is complex and difficult to clean, leakage and/or poor adhesiveness may occur according to the effect of the residue or the like, causing reliability to lower. Then, in the CMP apparatus that polishes a semiconductor substrate, roll scrub cleaning or pen scrub cleaning is carried out in a cleaning process after polishing. For example, Japanese Patent Laid-Open No. 2013-172019 describes such a technology.
In a conventional substrate cleaning apparatus, for example, a substrate front surface is cleaned while rotating the substrate placed flat in the horizontal direction. When a substrate is simply placed flat in the horizontal direction, the substrate becomes warped (into a concave shape) due to its own weight. The warped shape due to substrate's own weight, unfortunately, is more conspicuous as a substrate diameter becomes larger. For example, if a substrate diameter becomes 1.5 times larger (from 300 mm to 450 mm), a warpage amount in the central portion of the substrate becomes 2 to 3 times greater.
Also, when a substrate front surface is cleaned by pen scrub cleaning, the substrate is cleaned by a cleaning member that swings on the substrate front surface. In such a situation, when the cleaning member passes the central portion of the substrate front surface, if there is not a supporting member in the substrate rear surface, the substrate also becomes warped due to a pressing force by the cleaning member. This problem with the warped shape caused from the pressing force by the cleaning member may occur also when the substrate is placed vertically or obliquely, not limited to when the substrate is placed flat in the horizontal direction.
Once a substrate becomes warped, a variation in cleaning characteristic may occur between the central portion and the outer circumferential portion of the substrate. For example, if a substrate is placed flat in the horizontal direction, a scrubbing solution is discharged by centrifugal force generated by rotating the substrate, but if the central portion of the substrate becomes concave, discharging performance of the scrubbing solution lowers. The problem that the discharging performance of the scrubbing solution lowers has particularly a large effect on rinsing after cleaning by using a medical solution, accordingly, a margin in an integrated cleaning process may be reduced, a throughput may be lowered due to a long time processing and a high cost may be incurred because of consumption material.
Furthermore, once a substrate becomes warped, a variation in cleaning characteristic may occur between the central portion and the outer circumferential portion of the substrate also when pen scrub cleaning is carried out. That is, once a substrate becomes warped, a pressing force by a cleaning member lowers in the central portion of the substrate, and the cleaning characteristic may deteriorate in the central portion of the substrate (where a whirl speed is low). Then, if the pressing force by the cleaning member is simply strengthened, a corner of the cleaning member comes into contact with the outer circumferential portion of the substrate (where a whirl speed is high) and back contamination may increase.
Therefore, it has been desired to provide a substrate cleaning apparatus that can prevent a substrate from becoming warped when the substrate is cleaned by using a swing cleaning member.
A substrate cleaning apparatus of one embodiment includes a plurality of outer circumference supporting members that support outer circumference of a substrate; a swing cleaning member that swings between a first peripheral position and a second peripheral position of the substrate while passing a center portion of the substrate to clean a front surface of the substrate; and an elongated supporting member that extends long from a third peripheral position and a fourth peripheral position of the substrate so as to pass the center portion of the substrate and supports the rear surface of the rotating substrate, wherein one of the first peripheral position and the second peripheral position is disposed between a position of an outer circumference supporting member closest to the third peripheral position and the third peripheral position, or between a position of an outer circumference supporting member closest to the fourth peripheral position and the fourth peripheral position.
A substrate cleaning apparatus of another embodiment includes a plurality of outer circumference supporting members that support outer circumference of a substrate; a cleaning member for oscillating from/to an first peripheral position of the substrate through a center portion of the substrate to clean a front surface of the substrate; and an elongated supporting member that extends long from a third peripheral position and a fourth peripheral position of the substrate so as to pass the center portion of the substrate and supports the rear surface of the substrate, wherein the first peripheral position is disposed between a position of an outer circumference supporting member closest to the third peripheral position and the third peripheral position, or between a position of an outer circumference supporting member closest to the fourth peripheral position and the fourth peripheral position.
A cleaning sponge of the other embodiment includes a body portion having a lower surface thereof, the lower surface being to be contacted with the front surface of the substrate; and a neck portion to be provided to stand on an upper surface of the body portion; wherein at least one of a recess in a root end portion of the neck portion, a concave portion in the upper surface of the body portion, or a convex portion in the upper surface of the body portion is provided.